1. Field
The present invention relates to an image scanning apparatus and, more specifically, to improvement in an image scanning apparatus arranged to optically scan an original document transported from a containing unit.
2. Description of the Related Art
A technique for detecting, by using an ultrasonic sensor arranged to transmit ultrasonic sound towards an original document that is being transported, whether or not the original document that is being transported has been multiply fed, is being suggested. In such an image forming apparatus, by comparing a reception level of the ultrasonic sound that has passed through the original document with a threshold value, it is detected whether the original document that is being transported is in the singular or in the plural, i.e., whether or not the original document that is being transported has been multiply fed. Normally, when it is determined that the original document that is being transported has been multiply fed, the transportation of the original document is paused. In another apparatus, when multiple feeding is detected, a transportation speed is reduced in paper feeding of a next original document.
In such conventional apparatuses described above, when it is determined that the original document that is being transported has been multiply fed, the transportation of the original document is merely paused, or the transportation speed in the paper feeding of the next original document is merely reduced. Accordingly, a problem is that when it is determined that the original document that is being transported has not been multiply fed, paper jam or the like cannot be prevented from occurring in a transportation path.